148 Journal of the Mitchell Society [March 



body and to the vicinity of little veins of hornblende ciittino- thi-oiii-h 

 it. It is apparently most abundant where shearing has taken place. 

 From the main mass of the ore body the mineral is entirely absent, so 

 that it has no bad effect upon the ore. Through the ore are small 

 vein-like masses of coarse black hornblende or of hornblende and mag- 

 netite all running parallel to the schistosity of the ore, which is paral- 

 lel to the general strike of the ore body, thus accentuating the struc- 

 ture. In some cases there are also present in the limestone streaks of 

 magnetite that suggest very strongly little dikes. These are rarely 

 more than ly^ inches wide. Their walls are nowhere sharp, but on 

 the contrary on their margins the magnetite layers pass into the 

 marble by gradations, the carbonate grains becoming more and more 

 abundant toward the marble side of the contact until finally the rock 

 becomes essentially a nearly pure marble. The thin section shows the 

 magnetite streak to be an aggregate of carbonates, actinolite and mag- 

 netite, with the last named of course predominating. 



The mine has been operating for only a short time. About 500 

 carloads of ore had been shipped to Aug., 1919. At present the ex- 

 posed faces of ore suggest the existence of two sheets parallel to the 

 foliation of the country rocks. The explorations are not sufficiently 

 extended to show how far the sheets are continuous, consequently 

 there is no means of estimating the magnitude of the, reserve. The 

 lower sheet is believed to pinch out just beneath the floor of the tun- 

 nel, as is indicated in the cross section on pi. 25, but its extension in 

 other directions is entirely unknown. The upper sheet has been shown 

 by a raise to extend from the tunnel level to near the surface but there 

 is no evidence to show how far it extends beneath the tunnel or beyond 

 the sides of the raise. Although the vein looks more regular at its 

 present depth than it was nearer the surface, nevertheless there is no 

 certainty that it will not suddenly become broken and irregular. 



Origin of the Ore : — If the theory' with regard to the origin of the 

 Cranberry ore is correct, and the magnetite in this deposit is due to 

 deposition from ascending hot liquids and gases brought upward by 

 augitic pegmatites, then it se?ms probable that the marble ores are 

 likewise the result of pegmatitic solutions. Old limestones were meta- 

 morphosed by solutions depositing magnetite and producing horn- 

 blende and aiding in the development of garnet and actinolite from 



' Bavlev, W. S., The Magnptites of Xorth Oiirolina — Their Origin. Econ. Geol. v. IG, 

 no. 2, March, 1921, j.p. 142152. 



